PRELIMINARY SCREENING TO DETERMINE POTENTIAL ANTIMICROBIAL ACTIVITIES IN LEAF EXTRACTS OF MYRTACEAE FAMILY PLANTS: PSIDIUM GUAJAVA L. AND EUGENIA UNIFLORA L. AGAINST STREPTOCOCCUS AGALATIAE

MARINA NOVOSAK; FERNANDO BOBADILLA; ANALÍA KACHUK; ILIANA JULIETA CORTESE; DANIANA WINNIK; FERNANDO KRAMER; MARGARITA LACZESKI; MARINA QUIROGA

Foz do Iguacú- Paraná- Brasil

Congreso; 29º Congresso Brasileiro Microbiologia - CBM 2017.; 2017

Sociedade Brasileira de Microbiologia

Psidium guajava L. and Eugenia uniflora L. are native vegetal species from subtropicalAmerica, specially Argentina, Brazil, Paraguay and Uruguay. They are used in folk medicine forvarious purposes such as antihypertensive, antidiarrheal, diuretic, antioxidant and antimicrobial.Streptococcus agalatiae group B, commonly known as GBS, is an infective agent that affects humansand animals, particularly fish called Tilapia and livestock. GBS is classified by capsular phenotype inten identified serotypes: Ia, Ib, and II-IX. Of these, Ia is more frequently associated to infections inhumans. However, Ib and II are usually responsible in fish infections. Penicillin, macrolides,lincosamides and streptogramines are used for treating infections caused by this microorganism. Inrecent years, an increased resistance to these drugs has been reported. The emergence of resistanceagainst classical pharmacological treatments generates interest in the development of newalternatives. The aim of this work was to search for antimicrobial activity of leaf extracts of Psidiumguajava L. and Eugenia uniflora L. against GBS. Fifteen wild strains of GBS, serotypes Ia, Ib and II,were assayed with aqueous and ethanolic extracts of both plants. Vegetal samples were collected inOberá, Misiones Province (E. uniflora 27°540514 S; 55°168381 W and P. guajava 27°545146 S;55°164209 W). The extracts were obtained by controlled digestion at 37°C for 24 h and 48 h usingwater and ethanol, respectively. Streak plate disc diffusion test was performed inoculating a 0.5McFarland turbidity bacterial suspension on Müller-Hinton agar supplemented with blood. 2 mg ofextract were loaded on the discs. Minimal Inhibitory Concentration (MIC) test was performed by platemacrodilution test according to recommendations of Clinical and Laboratory Standards Institute(CLSI, 2015) and modifications by Su et al, 2015. Dimethyl Sulfoxide (DMSO) was used as negativecontrol. The range of extracts concentration tested was 0.0625 mg.mL-1to 30 mg mL-1. The ethanolicextracts of both species showed low inhibitory activity by the disc diffusion test (P. guajava L.7.1mm SD= 0.57 E. uniflora L. mm SD=0.60) whereas the aqueous extracts did not showinhibitory activity at all ( = 6mm SD=0 in both cases). For the case of P.guajava L. we were able toverify that the ethanolic extract shows lower MIC than the aqueous one (ethanolic 20.7 mg mL-1SD=2.67, aqueous ≥30 mg mL-1). Although it was impossible to do the MIC assay with E. uniflora L.aqueous extract at concentrations over 5 mg mL-1, because it spoils the growing media (ethanolic=23.57 mg mL-1 SD=4,97). We conclude that ethanolic extracts of both plants have potentialantimicrobial activity against GBS. The results indicate the need to continue with the studies and toadvance in the identification and characterization of responsible metabolites. It represents thepotential to develop a product with application in human medicine, livestock and / or pisciculture, withimpact not only on human health but economic to avoid or reduce the possibility of infections by GBSin livestock and fish.